Nod uses less resources but mcafee on my machine runs just as easy and fast as nod. so it is really up to the individual to trial and make their on decesion as to which runs the best on their machine. Simply because no program is going to run the same on my comp. as it does on yours or someone elses.

I found a very significant difference re CPU usage, but this did not translate, most importantly, to any meaningful experienced difference in performance.

On an XP Pro system with a P4 2.66GHZ CPU, McAfee VirusScan 8 regularly hit 100% CPU usage, indeed, it seemed to hit 100% whenever it was called into action. NOD32 is effectively invisible re CPU usage in normal use - CPU time at present for all NOD processes, for instance, is less than 2½ minutes in 52 hrs of uptime (I am not running VirusScan at present so cannot give equivalent figures). On the other hand, this type of difference in CPU usage had no noticeable impact on performance - VirusScan was mightily impressive in my view as a scanner, but I found its lack of configurability to be frustrating and its dependence on IE/ActiveX somewhat perverse for a long time user of Mozilla/Firefox.

In sum, while I could use, for instance, Process Explorer to examine the difference between McAfee and NOD32, in reality this is a completely empty exercise as both a-vs run here without impacting negatively on anything I wish to do on my machine and CPU usage has played no part what so ever in my choice of NOD32 over VirusScan for normal, daily use.

He's asking about CPU usage,not general resource usage. To see this,just enable CPU Time column in Taks Manager. Honestly,AVs don't use much CPU at all. Those 100% that you were seeing with McAfee don't mean anything. And 100% in task manager doesn't mean actual 100% CPU utilization...

EDIT:
NOD32 2.5 after around 1 day of running used only 30 seconds of CPU time.
Thats nothing...